Contributions to the theory of magnetorotational instability and waves in a rotating plasma

The one-fluid magnetohydrodynamic (MHD) theory of magnetorotational instability (MRI) in an ideal plasma is presented. The theory predicts the possibility of MRI for arbitrary 0, where 0 is the ratio of the plasma pressure to the magnetic field pressure. The kinetic theory of MRI in a collisionless plasma is developed. It is demonstrated that as in the ideal MHD, MRI can occur in such a plasma for arbitrary P. The mechanism of MRI is discussed; it is shown that the instability appears because of a perturbed parallel electric field. The electrodynamic description of MRI is formulated under the assumption that the dispersion relation is expressed in terms of the permittivity tensor; general properties of this tensor are analyzed. It is shown to be separated into the nonrotational and rotational parts. With this in mind, the first step for incorporation of MRI into the general theory of plasma instabilities is taken. The rotation effects on Alfven waves are considered.

A spill-over theory of international trade unionism

This paper use neo-functionalist and institutionalist theories of geo-political integration to develop a theory of international trade unionism. In brief, the theory asserts that the type of international ‘context’ in which international trade unions operate presupposes the types of ‘imperatives’ that will dominate their interests and concerns. These imperatives are taken to operate along one of three dimensions - industrial, political and ideological, and are seen as evolving in accordance with the ‘logic of spill-over’ in global and sub-global integration processes. Using this interpretation the discussion provides reasons as to why ideological imperatives have historically dominated international trade union thinking, the only exception being regional trade unions operating in Europe, which have evolved beyond the ideological to embrace industrial and political imperatives in their modes of organisation and operation.

Sport-based entrepreneurship : towards a new theory of entrepreneurship and sport management

The entrepreneurship and sport management disciplines have grown significantly in the past decade. Sport is an entrepreneurial process as innovation and change are key elements of sport. The aim of this paper is to develop a theory of entrepreneurship in sports management by investigating the relationship between entrepreneurship and sport. The rapidly growing and developing sport marketing discipline provides a basis in which to understand how entrepreneurship occurs through innovation, proactiveness and risk taking activities. This paper discusses the connection between the entrepreneurship and sports management fields and argues that there needs to be more integration with the two fields of study and traditional entrepreneurship theory. A theory of sport-based entrepreneurship is developed and different types of entrepreneurship that occur in sports management are examined. Suggestions for future research and implications for practitioners are discussed.

Towards global benchmarking of food environments and policies to reduce obesity and diet-related non-communicable diseases : design and methods for nation-wide surveys

Introduction: 

Toward a receiver-based theory of knowledge sharing

Managers and researchers alike have sought new ways to address the challenges of sharing dispersed knowledge in modern business environments. Careful consideration by sharers of receivers' knowledge needs and behaviours may improve the effectiveness of organisational knowledge sharing. This research examines how sharers react to their perceptions of receivers' knowledge needs and behaviours when making choices relating to sharing knowledge. The focus of this article is to propose and empirically explore a theoretical framework for a study of the role of the receiver in knowledge sharing - receiver-based theory. Data collected from two case studies highlight a key role played by perceived receiver knowledge needs and behaviours in shaping sharer choices when explicit knowledge is shared. A set of receiver influences on knowledge sharing is provided that highlights key receiver and sharer issues. The paper concludes that companies should develop better ways to connect potential sharers with receivers' real knowledge needs. Further, the findings suggest that sharing on a need-to-know basis hinders change in organisational power structures, and prevents the integration of isolated pockets of knowledge that may yield new value. © 2008, IGI Global.

Towards a theory of the small firm: theoretical aspects and some policy implications

Includes bibliography

Discrimination of media moments and media intervals: sticker-based watch-and-comment annotation

In this paper we discuss the problem of how to discriminate moments of interest on videos or live broadcast shows. The primary contribution is a system which allows users to personalize their programs with previously created media stickers-pieces of content that may be temporarily attached to the original video. We present the system's architecture and implementation, which offer users operators to transparently annotate videos while watching them. We offered a soccer fan the opportunity to add stickers to the video while watching a live match: the user reported both enjoying and being comfortable using the stickers during the match-relevant results even though the experience was not fully representative.

How Minds Work: A Cognitive Theory of Everything - a Tutorial on the IDA Model of Cognition

The IDA model of cognition is a fully integrated artificial cognitive system reaching across the full spectrum of cognition, from low-level perception/action to high-level reasoning. Extensively based on empirical data, it accurately reflects the full range of cognitive processes found in natural cognitive systems. As a source of plausible explanations for very many cognitive processes, the IDA model provides an ideal tool to think with about how minds work. This online tutorial offers a reasonably full account of the IDA conceptual model, including background material. It also provides a high-level account of the underlying computational “mechanisms of mind” that constitute the IDA computational model.

Barry Saltzman and the Theory of Climate

Barry Saltzman was a giant in the fields of meteorology and climate science. A leading figure in the study of weather and climate for over 40 yr, he has frequently been referred to as the "father of modern climate theory." Ahead of his time in many ways, Saltzman made significant contributions to our understanding of the general circulation and spectral energetics budget of the atmosphere, as well as climate change across a wide spectrum of time scales. In his endeavor to develop a unified theory of how the climate system works, lie played a role in the development of energy balance models, statistical dynamical models, and paleoclimate dynamical models. He was a pioneer in developing meteorologically motivated dynamical systems, including the progenitor of Lorenz's famous chaos model. In applying his own dynamical-systems approach to long-term climate change, he recognized the potential for using atmospheric general circulation models in a complimentary way. In 1998, he was awarded the Carl-Gustaf Rossby medal, the highest honor of the American Meteorological Society "for his life-long contributions to the study of the global circulation and the evolution of the earth's climate." In this paper, the authors summarize and place into perspective some of the most significant contributions that Barry Saltzman made during his long and distinguished career. This short review also serves as an introduction to the papers in this special issue of the Journal of Climate dedicated to Barry's memory.

Global models of planet formation and evolution

Despite the strong increase in observational data on extrasolar planets, the processes that led to the formation of these planets are still not well understood. However, thanks to the high number of extrasolar planets that have been discovered, it is now possible to look at the planets as a population that puts statistical constraints on theoretical formation models. A method that uses these constraints is planetary population synthesis where synthetic planetary populations are generated and compared to the actual population. The key element of the population synthesis method is a global model of planet formation and evolution. These models directly predict observable planetary properties based on properties of the natal protoplanetary disc, linking two important classes of astrophysical objects. To do so, global models build on the simplified results of many specialized models that address one specific physical mechanism. We thoroughly review the physics of the sub-models included in global formation models. The sub-models can be classified as models describing the protoplanetary disc (of gas and solids), those that describe one (proto)planet (its solid core, gaseous envelope and atmosphere), and finally those that describe the interactions (orbital migration and N-body interaction). We compare the approaches taken in different global models, discuss the links between specialized and global models, and identify physical processes that require improved descriptions in future work. We then shortly address important results of planetary population synthesis like the planetary mass function or the mass-radius relationship. With these statistical results, the global effects of physical mechanisms occurring during planet formation and evolution become apparent, and specialized models describing them can be put to the observational test. Owing to their nature as meta models, global models depend on the results of specialized models, and therefore on the development of the field of planet formation theory as a whole. Because there are important uncertainties in this theory, it is likely that the global models will in future undergo significant modifications. Despite these limitations, global models can already now yield many testable predictions. With future global models addressing the geophysical characteristics of the synthetic planets, it should eventually become possible to make predictions about the habitability of planets based on their formation and evolution.